Nasal and oral filters

ABSTRACT

A nasal device for sampling inhaled particulate matter in the nose of a person to allow identification of aeroallergens in the inhaled matter or to prevent disease states mediated by such aeroallergens. The nasal device has a body adapted to fit within a person&#39;s nostril and to resiliently engage its inside wall. A passage extends through the body to allow air to be inhaled by the person through the nasal device. The passage has a non-linear path and includes a sample collection zone placed in the passage so that, during inhalation, air is drawn firstly towards and then secondly around the collection zone so that a sample of any particulate matter in the inhaled air will be caused to impact against the collection zone due to the non-linearity of the passage and to be retained on the collection zone, the sample collection zone being removable from the nasal device to allow analysis of the matter impacted thereon.

This application is a 371 of PCT/AU95/00540 filed Aug. 25, 1995.

FIELD OF THE INVENTION

The present invention relates to nasal and oral filters and moreparticularly to nasal filters adapted to recover fine particulatematerial from air inhaled or exhaled by a human or other mammaliananimal.

BACKGROUND ART

Many people, and other mammalian animals, suffer from asthma, rhinitisand other diseases caused by the inhalation of aeroallergens. In orderto understand the nature of the disease and possible treatments it wouldbe desirable to be able to collect these aeroallergens from the inhaledair stream. Such collections could also act as a prophylactic measure.

While there is strong epidemiological evidence associating exposure toaeroallergens to both sensitisation and symptoms at a communal level,and to a lesser extent at an individual level, the methods forestimating personal exposure to aeroallergens are poorly developed. Themost common method is to measure allergen concentration in settled dust(collected by a vacuum cleaner) which functions as a source ofaeroallergens. The method has, however, serious confounders such as theconcentration of allergen and quantity of dust/area varying more than 10fold at different sites within a room. There is, however no data todirectly show that such samples relate to individual personal exposure.Others have attempted to measure aeroallergens on stationary filtersusing an air pump. With this method the amount of aeroallergen per timeor volume differs markedly with degrees of dust disturbance and pumpflow rates. Generally, measurement of settled and airborne dustcorrelate only weakly with one another, if at all. Outdoor allergensources, such as fungal spores or fallen particles, are estimated andgeneralised with spoor traps.

The best available method generally used to measure personal exposure isto use filters worn on the upper body. These were developed foroccupational sampling eg. for asbestos and coal. Although they have beenused occasionally for allergens they cannot be widely applied. Thisapplication is limited by battery life, low flow rates, consequent smallsamples and the relatively high cost of such sampling devices. Suchfilters may not reflect what is actually being inhaled for severalreasons. Firstly, spatial distribution of allergenic particles differsover small distances. For instance, in bed the face is close to theallergen source and the allergen may not travel to a filter a half metreaway. Secondly, the collection of particles onto a vertical filtersurface with a low constant face velocity is significantly differentfrom such a collection involving variable airflow into a person'snostrils. Variables include changes in flow between and within eachcycle of respiration and with exercise, and the effects of thermal bodydrafts, movement and wind.

Airborne allergens are mainly carried by large particles, although thisvaries with both the allergen involved and the circumstances. Miteallergens are mainly carried by mite faeces (>90% allergen10-40μparticles); cat allergens with dander particles (˜70% associatedwith >˜3μ particles); fungal allergens depend upon the species andmaturity (3 to 90μ); pollen depending upon the species (15 to 60μ,mainly 20 to 30μ). What is airborne is dynamic and changes with time;small particles, for instance, have lower settling speeds and remainairborne for longer.

The nose of humans and other mammalian species efficiently collectsparticles, such as dust, pollen, and bacteria, onto the mucosa by acombination of turbulence and impaction. Efficiency is determined byparticle velocity, angular velocity, mass, size and shape of theparticle and the route that the particle takes in the nose.

There have been reports (Pasricha J. S. & Abrol B. M. Ann. Allergy 1974;32:331-333; French Patent specifications 2,536,659, and 2,504,003; U.S.Pat. Nos. 4,401,117 and 5,117,820) of the insertion of a tube containinga filter such as a wire mesh sieve into the nose for the purpose ofrelief of inhalant allergy. The use of such a wire filter with a poresize capable of removing most particles associated with allergy (ie.those >5μ diameter) could be expected to have high airflow resistanceand to be uncomfortable to use. In addition, as such a filter becomesloaded with particles its resistance would increase making it moredifficult to use. In addition particulate material collected by suchfilters would be more difficult to completely remove in an unadulterated(virgin) state and so would not be in a form suitable for directanalysis.

DISCLOSURE OF THE INVENTION

In its broadest aspect the invention consists in particle entrapmentmeans for the capture of particles in an inhaled or exhaled air stream,the particle entrapment means comprising a body having a portion adaptedto fit within the mouth or at least one nostril of a human, or othermammalian animal, in sealing engagement with the edges of that orifice,and a passage through the body to allow air to be inhaled or exhaled bythe animal through the particle entrapment means, the passage having anon-linear path, being of a minimum cross sectional area very muchlarger than the maximum cross sectional area of the particulate matterlikely to be entrapped and including collection means so placed in thepassage that, in use, particulate matter in air inhaled by or exhaledby, the animal will be caused to impact against the collection means dueto the non-linearity of the passage and to be retained on the collectionmeans.

The principle use of the devices according to this invention is thecapture of potentially allergenic particles in inhaled air. The devicesmay also be used to collect particles in exhaled air. The exhaled airmay contain shed viruses or mycobacteria indicative of particularrespiratory disease states. Such collected particles could be subject todiagnostic procedures such as by culture, by antibody probing or bynucleic acid analysis.

The non-linear passage through the particle entrapment means is adaptedto allow substantially free inhalation and/or exhalation at least when awearer is at rest. For this reason the passage is very much larger incross sectional area than the maximum cross sectional area of theparticles likely to be entrapped. Preferably the cross sectional area ofthe passage will be many orders of magnitude greater than thecross-sectional area of the individual particles of interest. Typicallysuch particles have cross-sectional areas of from 3 to 2000 sq μm (i.e.the particles have diameters from 1 to 50 μm). Typically thecross-sectional area of the passage is at least 5 sq mm, preferably 10sq mm. The nasal filter may be provided with a small number of passages,preferably no more than 5, rather than a single passage. In this case itis preferred that the total cross-sectional area of the passages amountsto at least 7 sq mm and more preferably at least 10 sq mm.

The particle entrapment means will preferably be such that the inlet tothe passage will, in use, be positioned closely adjacent to the orificeinto which the means is fitted. In this way it is ensured that the airpassing through the passage is representative of the air that the userwould have inhaled were the means not in use. The trapped particles arethus representative of particles that are inhaled by the user.

In one form of the invention the entrapment means may be acigarette-like device adapted to fit into a users mouth. The lips mayseal around an end of the body so that inhaled air is drawn through thepassageway.

In another form of the invention the particle entrapment means isinserted into a nostril of a user. In this aspect the invention consistsin a nasal filter comprising a body adapted to fit within a nostril of ahuman, or other mammalian animal, means to cause an outer surface of thebody to resiliently engage an adjacent surface of a nostril into whichthe nasal filter is positioned so as to retain the nasal filter in thenostril, and a passage through the body to allow air to be inhaled bythe animal through the nasal filter, the passage having a non-linearpath and including collection means so placed in the passage that, inuse, particulate matter in air inhaled by the animal will be caused toimpact against the collection means due to the non-linearity of thepassage and to be retained on the collection means.

In another aspect the present invention consists in a method for thecapture of particulate matter passing through the mouth or a nostril ofa human or other mammalian animal comprising inserting into the mouth ora nostril of the animal a particle entrapment means according to thisinvention and causing the animal to inhale through said mouth ornostril.

As the preferred form of the invention is the nasal filter form thefollowing specification will generally concentrate on this form of theinvention. It is to be understood that the invention is generallyapplicable to particle entrapment means for insertion into either themouth or nostrils.

The method and filter according to the present invention may be used tocollect particles of various origins, including biological, organic ormineral, for sampling. Some examples would include pollens,microbiological material, dander, debris, dust of all sorts, asbestosfibres and spores which can later be removed from the nasal filter foranalysis. They may also be used to collect particles to prevent exposureto the particles through inhalation. The filters can thus have atherapeutic, protective or prophylactic function. As one example thenasal filter and method according to this invention could be used toreduce exposure to allergens and thus reduce symptoms of hay fever.

While the invention will have most applicability to humans it may alsobe used in the diagnosis and/or treatment of similar aeroallergendiseases in other mammalian animals. It may have particularapplicability in racing horses or dogs, in prize livestock and inhousehold pets.

The body of the nasal filter may be formed of resilient material such asa soft plastics material, a natural or synthetic rubber or a siliconematerial. Alternatively it may be made of a rigid material such as arigid synthetic plastics material or a metal. In the latter case it isprovided with a resilient surface coating or layer. Alternatively, itmay be provided with a resilient foam or inflatable cuff. The use ofsuch a cuff has the advantage that a single filter may be adapted foruse in persons with a wider range of nostril sizes than would otherwisebe possible. In each case the body of the nasal filter is provided withmeans to allow it to resiliently engage with the internal surface of anostril into which it is inserted. It is desirable, though notessential, that the body of the nasal filter forms an hermetic seal withthe internal surface of the nostril. The length is preferably shortenough to fit fully within a nostril. There may, however, be occasionsin which it is desirable, or necessary, to make a nasal filter of such alength that it will protrude from a user's nostril. The filters arepreferably clear or flesh coloured to be unobtrusive to a wearer'sappearance.

The passage through the body may have any one or many differentconfigurations. The passage should be non-linear to such an extent thatit will induce, in inhaled air, movement which will cause deposition ofat least some of the particles in the inhaled air on the collectionmeans. The particles may be caused to impact on the collection means dueto their inertia causing then to continue in a straight line and impacton the collection means as the air changes direction. Alternatively theparticles may impact on the collection means due to centrifugal forcesgenerated by the swirling of the air stream.

Inhaled air will be drawn into the wearer through the passage in thenasal filter. The wearer may also exhale through that passage.Alternatively, the wearer may exhale through a second outflow passage inthe nasal filter or through the mouth. Similarly if inhalation through aparticle entrapment means positioned in the mouth exhalation may bethrough the nose, through the inhalation passage in the entrapment meansor through a separate exhalation passage therein.

The collection means may comprise a small designated area inside thepassage or may comprise all of its surface area. In one preferredembodiment of the invention the passage is bifurcated in a downstreamdirection. In this embodiment the collection means comprises a surfacein axial alignment with the common part of the passage, the collectionmeans being located between the two divergent arms of the passage at thepoint of bifurcation.

In preferred embodiments of the invention the surface of collectionmeans may be ribbed or otherwise fashioned in a shape to enhanceparticle collection. Alternatively the surface may be coated with anadhesive or another substance that will enhance particle collection. Ifdesired the collection means may comprise a strip, patch or other pieceof material that may be readily removed from the nasal filter. Inanother preferred embodiment the collection means may comprise a disc ofa gel, or a well containing a liquid, that may be transferred directlyto an immunoassay for allergens. The collection means may also betreated to neutralise or in some other way react with the particlesimpacting thereon.

If desired more than one collection means may be provided in the nasalfilter. The filter may include a surface to collect particles having afirst set of characteristics and another surface to collect particleswith another set of characteristics. Thus one may capture very smallparticles of, say, less then 3μ diameter in one part of the filter andanother may capture larger particles in another part of the filter.

In the case that the nasal filter is to be used to collect particles foranalysis it may be desirable that the nasal filter may be taken apart tofacilitate recovery of collected particles from the collection means. Itmay also be of advantage to form the nasal filter in a number of partsto allow adjustment of the nature of the passage. Such a change mayenable the collection of particles only of some preferred size ordensity. For example one may desire to only collect particles greaterthan 10μ or less than 3μ in diameter. There may also be advantage inchanging the shape of the passage to adjust for the likely air flowvelocity. In one configuration the passage may be adapted to bestcollect particles under high flow rates and in another configuration itmay best collect particles at low flow rates. The passage and/or thecollection means may be so constructed that it, or they, change shapewith changed flow velocities. Such change may be adapted to maintainsubstantially constant particle collection characteristics or breathingresistance. The collection means could for example be mounted on aresilient mounting, such as a rubber foam, which will move closer to theinlet at low flow rates and further away at high flow rates.

In another embodiment the passage is adapted to change shape as the airflow changes from inhalation to exhalation. In this way exhalation maybe facilitated.

In normal use a nasal filter would be positioned in each of the animal'stwo nostrils. In order to facilitate insertions and removal of thefilters they are preferably joined by a bridge at the distal ends. Thebridge may comprise a relatively rigid bridge adapted to hold the twofilters in an appropriate relationship to one another. Alternativelythey may be handled separately and be joined by an entirely flexiblebridge such as a ribbon or thread.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter by way of example only is a preferred embodiment of theinvention described with reference to the accompanying drawings inwhich:

FIG. 1a is a partly cut-away, schematic, side elevational view of theface of a person in whose nostrils had been inserted a nasal filteraccording to the present invention;

FIG. 1b is an underneath view of the nasal filters of FIG. 1a;

FIG. 1(c) is a partly cut-away, schematic, side elevational view of theface of a person in whose mouth has been inserted a nasal filteraccording to the present invention.

FIG. 2a is a vertical sectional view through a nasal filter according tothe present invention;

FIG. 2b is a schematic perspective view of the nasal filter of FIG. 2ashowing the passage therethrough as though the body of the nasal filterwere transparent, and

FIGS. 3a to 3e shows vertical sectional views through nasal filtersaccording to five different embodiments of the present invention, FIG.3f is a vertical section through the nasal filter of FIG. 3c at 90° tothe plane of that figure.

BEST MODE FOR PERFORMING THE INVENTION

The nasal filters 10 according to the present invention are preferablyinserted into each nostril 11 in the nose 12 of a user. The two filters10 are preferably joined at their distal ends by a flexible bridge 13.The bridge 13 facilitates withdrawal of the filters from the nose 12.

As is seen in FIG. 2(a) the nasal filter 10 is formed with an airpassage 14 which comprises a y-shaped channel extending longitudinallythrough a body 15 of the nasal filter 10. The passage 14 includes aninlet 16 of gradually diminishing cross-section in the direction of flowof inhaled air. The inlet 16 terminates at a point of bifurcation of thepassage 14 to form a pair of outlets 17. A substantially planarcollection area 18 for entrained particulate matter is formed in axialalignment with the inlet 16. The collection area in the depictedembodiment is coated with an adhesive or another substance that willenhance particle collection.

The body is formed of a resilient synthetic plastics material in twoparts. The body has a resilient surface coating or layer 24, or may besurrounded by a resilient cuff 25 of a foam material or which isinflatable. An upper part 19 defines a portion of the outlets 17 and thecollection area 18. The lower part 21 defines the inlet 16 and a portionof the outlets 17. The parts 19 and 21 are resiliently retained togetherby interengaging flanges 22.

In use two of the nasal filters 10 are inserted into the nose of a useras is shown in FIGS. 1(a ) and 1(b). As depicted in FIG. 1(c), thefilter 10 can instead be inserted into the mouth 9 of a user, ifdesired. The user breathes through the nasal filters 10 for a period tocollect a sample of inhaled aeroallergens or while he or she is in anenvironment that may contain potentially deleterious aeroallergens. If asample of aeroallergens is to be taken the nasal filters 10 can beremoved from the nose and separated into its upper and lower portions 19and 21. The collection area 18 is then exposed and the impactedparticulate matter therein recovered for analysis. These particles willhave been entrained in inhaled air (as shown by arrows A) andaccelerated as they pass through the inlet. As the inhaled air isdiverted from its linear path at the bifurcation of the passage 14 atleast some of the particles will proceed straight ahead and strike thecollection area 18 which is coated with an adhesive or another substance26 that will cause particles to adhere thereto and enhance particlecollection. The air will continue through the nasal filter and emergefrom the outlets 17 (as shown by arrows B).

The nasal filters shown in FIGS. 3(a)-3(f) are essentially similar tothat described with reference to FIGS. 2(a) and 2(b) and similar partshave been identified by similar numeric indications. The nasal filtershown in FIG. 3(b) has two primary collection areas 18 which are adaptedto collect particles of differing sizes. The passage 14 of the nasalfilter 10 of FIG. 3(c) and 3(f) includes a swirl or vortex chamber 23.The collection area forms the circumferential wall of the swirl chamber23. The passage 14 of the nasal filter 10 of FIG. 3(d) is helical andsubstantially any part of the helix could form the collection area 18under appropriate flow conditions.

The impacted particulate matter may be recovered by scraping thematerial from the collection area 18 by washing or blowing it therefrom.Thus in those cases, such as the passage 14 in FIGS. 3(c), 3(d) and3(e), where the collection area 18 is large and/or the passage 14 veryconvoluted it is still possible to recover samples for analysis.Alternatively, as described above, a strip or patch of removablematerial 27 may cover the collection means. In this case, the impactedparticulate matter is collected for analysis by removing the strip orpatch from the filter body.

If the filter body is formed in two portions (FIG. 2(a)) these may beconnected together by a screw thread to allow the relative positions ofthe two portions to be adjusted. In this way it is possible to changethe size and/or shape of passage. The size and type of particlesimpacting on the collection area may be influenced and adjusted.

I claim:
 1. Particle entrapment means for the sampling of particles inan inhaled, or an exhaled, air stream to allow identification of one ormore components of the air stream, the particle entrapment meanscomprising a body having a portion adapted to fit within the mouth or atleast one nostril of a human, or other mammalian animal, in sealingengagement with the edges of that orifice, and a passage through thebody to allow air to be inhaled by, or to be exhaled by, the animalthrough the particle entrapment means, the passage having a non-linearpath and including a sample collection means placed in the passage sothat, during inhalation, air is drawn firstly towards and then secondlyaround the collection means so that a sample of any particles in theinhaled air by the animal will be caused to impact against thecollection means due to the non-linearity of the passage and to beretained on the collection means, said sample collection means beingremovable from the entrapment means to allow analysis of the particlesimpacted thereon.
 2. A nasal device for sampling inhaled particulatematter to allow identification of one or more components of the inhaledmatter, the nasal device comprising a body adapted to fit within innostril of a human, or other mammalian animal, means to cause an outersurface of the body to resiliently engage an adjacent surface of anostril into which the nasal device is positioned so as to retain thenasal device in the nostril, and a passage through the body to allow airto be inhaled by the animal through the nasal device, the passage havinga non-linear path and including a sample collection means placed in thepassage so that, during inhalation, air is drawn firstly towards andthen secondly around the collection means so that a sample of anyparticulate matter in the inhaled air will be caused to impact againstthe collection means due to the non-linearity of the passage and to beretained on the collection means, said sample collection means beingremovable from the nasal device to allow analysis of the matter impactedthereon.
 3. The nasal device as claimed in claim 2 in which the body ofthe device is made of a resilient material selected from the groupconsisting of soft plastic material, natural rubber, synthetic rubberand a silicone material.
 4. The nasal device as claimed in claim 3 inwhich the body forms an hermetic seal with an inside surface of anostril into which it is inserted.
 5. The nasal device as claimed inclaim 2 in which the body is formed of a rigid material and is providedwith a resilient surface coating or layer.
 6. The nasal device asclaimed in claim 2 in which the body is surrounded by a resilient cuffof a foam material or which is inflatable.
 7. The nasal device asclaimed in claim 2 in which the passage is bifurcated in a downstreamdirection.
 8. The nasal device as claimed in claim 7 in which thecollection area is positioned in axial alignment with an inlet portionof the passage and is positioned between the bifurcated outlet portionsthereof.
 9. The nasal device as claimed in claim 2 in which thecollection means is formed with ribs or is otherwise fashioned to ashape to enhance particle collection.
 10. The nasal device as claimed inclaim 2 in which the collection means is coated with an adhesive oranother substance that will enhance particle collection.
 11. The nasaldevice as claimed in claim 2 in which the collection means is selectedfrom the group consisting of a strip, patch and other piece of materialthat may be readily removed from the nasal device.
 12. The nasal deviceas claimed in claim 2 in which the passage contains at least twodiscrete collection means.
 13. The nasal device as claimed in claim 12in which each of the at least two collection means collect entrainedparticles of different characteristics.
 14. The nasal device as claimedin claim 2 in which the body is formed in two or more parts that may betaken apart to facilitate recovery of collected particles from thecollection means.
 15. The nasal device as claimed in claim 2 in whichthe body of the nasal device is connected to the body of another similardevice by a bridge formed at their distal ends.
 16. The nasal device asclaimed in claim 2 wherein the collection means is substantially planar.17. The nasal device as claimed in claim 2 wherein the passage has anair outlet defining an area and the collection means has an area lessthan the area of the air outlet.
 18. The nasal device as claimed inclaim 2 in which the shape of the passage is as shown in FIG. 2(a). 19.The nasal device as claimed in claim 2 in which the shape of the passageis as shown in FIG. 3(a).
 20. The nasal device as claimed in claim 2 inwhich the shape of the passage is as shown in FIG. 3(b).
 21. The nasaldevice as claimed in claim 2 in which the shape of the passage is asshown in FIG. 3(c).
 22. The nasal device as claimed in claim 2 in whichthe shape of the passage is as shown in FIG. 3(d).
 23. The nasal deviceas claimed in claim 2 in which the shape of the passage is as shown inFIG. 3(e).
 24. The nasal device as claimed in claim 2 in which the shapeof the passage is as shown in FIG. 3(f).
 25. A method for the samplingof particulate matter passing through the mouth or a nostril of a humanor other mammalian animal comprising inserting into the mouth or anostril of the animal a particle entrapment means according to claim 1and causing the animal to inhale through said mouth or nostril.